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Motorcyclists have always been looking for ways to make their bikes go faster, and one way of doing it is making the engine bigger. Either by increasing the bore or the stroke. As Indian V-Twin cylinders can't be overbored (the valves are in the way), increasing the stroke has traditionally been the way to go when making big Indian engines. These engines are called strokers.

As the Scout has always been the most sporty of Indians, stroked 101s and Sport Scouts (SS) have always been popular. One way of doing it was to take flywheels from the opposition's WL-series 45" models using special shafts to allow them to fit in the Scout cases. These flywheels have shorter stroke than the Chief flywheels that were also sometimes used. The shorter stroke wheels are said to make for a more rev happy engine keeping with the lively nature of the original Scout engines, but this is perhaps debatable. Sportster (XL) flywheels are the same stroke, but beefier (and have stronger rods), and work well in 741s and Sport Scouts. These days, 741 has become possibly the most popular model for stroking.

Note: None of this stuff is really "bolt-on", and if you don't have access to a machine shop (and know how to use it), you are better off letting IPE or another competent Indian engine rebuilder do it for you. Email me if you need advice on this.

See below for detailed info on each setup, and links to shopping lists.

Click photos to enlarge

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IPE pinion- and drive shafts for H-D WL 45" flywheels in 101 cases, giving 45"/750 cc with 37"/600cc cylinders and 50"/811cc with 45"/750cc cylinders. Big, round items top left and right are TWAWL adapters to allow stock Indian thrust washers to be used. See table below for details. Little screw, in the middle at the bottom of the photo is the special L/H oil feed screw for 101 pinion shafts (fits both stock and stroker shafts). IPE stroker parts for 741 and SS work along the same basic lines. See notes below for more details, including info on flywheel modifications. Also links to complete parts (shopping) lists for each combo (101, 741 and SS with WL or Sportster flywheels)

WL/XL flywheels are narrower than Indian flywheels, but there are ways of making up for this in connection with the thrust washers either side of the wheels. I suggest using a special IPE thrust washer adapter (P/N TWAWL) for some applications. The thrust washer/ adapter thing can be a little confusing, but I hope this table will help. You must of course use the correct thickness thrust washers to get the correct end play on the crank assy, but this part of the job is just like building an engine with stock flywheels. Any questions, just ask! If you are a machinist, you can probably devise a way to bypass most of this and come up with your own thrust washer arrangement.
Thrust washers and adapters Pinion side Drive side
101 with WL flywheels  PHOTO Use IPE TWAWL adapter + 27B174 thrust washer in relevant thickness. Use IPE TWAWL adapter + 27B174 thrust washer in relevant thickness.
741/SS with WL flywheels  PHOTO Use IPE TWAWL adapter + 27B174 thrust washer in relevant thickness. Use stock WL thrust washer in relevant thickness.
741/SS with XL flywheels  PHOTO Lathe cut new recess for 27B174 thrust washer + use special, longer IPE pinion housing to make up for narrow flywheel assy. Lathe cut new recess in flywheel face for 27B174 thrust washer in relevant thickness.
27B174 is the stock Indian flywheel thrust washer for Chief and 45" 101. Available in various thicknesses for setting the end float.
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Stroker pistons for 45"/750cc 101. They come with rings, pins and clips (not in photo). 

Stroker pistons are also available for 37"/600cc 101 and 741. Note that these smaller pistons will "pop up" approximately 4mm at TDC so heads must be relieved for clearance. PHOTO here.

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741 and Sport Scout with WL flywheels. Adapters come with screws and pins. The adapters in these photos were not drilled for the flywheel retaining pins, but they will be drilled and pins fitted before being sent out. Retainer screws are M4x0.7. If you live in a "non metric" country and can't find a tap for this locally, let me know and I'll send you one with your stroker parts. Use 3.3 mm drill.
Click to view full-size
741 and Sport Scout with Sportster wheels. No adapters here, but flywheels must be modified to take Indian thrust washers. Special, longer pinion housing left in photo, centralizes narrow XL flywhels and allow line honing of main bearings.
IPE has Parts for these Stroker Setups: 
101 (37" G and 45" GP) with WL flywheels and rods.
741 and Sport Scout with WL flywheels and rods. 
741 and Sport Scout  with XL flywheels and rods.
More info below - including links to complete parts and price lists.
There are other ways of making 741s faster (cheaper and maybe a bit easier, but not as all-out, old-school cool as a stroker!). Big bore pistons and big valves help a lot. See the 741 parts page. IPE Electronic Ignition is a big help for any Indian, not least a tuned - or stroked - one, where bad ignition timing may have more serious consequences. Good examples of pretty powerful stock-stroke 741s here and here.

Stroker 101 with WL flywheels (750 cc).
To build a 45"/750cc 101/WL stroker from a 37"/600 cc engine, you will need the major parts below. Click here for a complete list of all parts needed.
1) Used WL flywheels. See notes on second-hand Harley parts below.
2) New WL crankpin and big end assy. Get these from a reputable supplier of Harley parts. I will see if I can't find a way to start having these parts in stock in the future, so you can get everything you need here.
3) Used WL rods. See notes on second-hand Harley parts below.
4) IPE Stroker pinion shaft, P/N 28B53WL.
5) IPE Stroker drive shaft, P/N 20B96WL.
6) IPE thrust washer adapters, P/N TWAWL - you will need two of these. 
7) IPE Stroker Pistons, P/N 75494S. Note that these pistons have a 4 mm (approximately) "pop-up" like the factory Bonneville pistons, and need the cylinder heads to be cut out for this. 
Complete parts list and tech info for 750cc Stroker 101
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Picture shows stroker piston pop-up at TDC like on factory Bonneville pistons. Heads must be relieved for this. This applies to stroker pistons for 37"/600cc Scouts and 741 (741 cylinders will have to be bored to 600cc size ~ 70mm to use these pistons). These engines will end up as 45"/750cc. Never mind the funny manifold nipple on this cylinder; just another experiment...
Stroker 101 with WL flywheels (811 cc).
To build a 50"/811cc 101/WL stroker from a 45"/750 cc engine, you will need the major parts below. Click here for a complete list of all parts needed.
1) Used WL flywheels. See notes on second-hand Harley parts below.
2) Used WL rods. See notes on second-hand Harley parts below.
3) New WL crankpin and big end assy. See note above.
4) IPE Stroker pinion shaft, P/N 28B53WL.
5) IPE Stroker drive shaft, P/N 20B96WL.
6) IPE thrust washer adapters, P/N TWAWL - you will need two of these. 
7) IPE Stroker Pistons, P/N 27C121S. No "pop-up" on these pistons so cylinder heads do not need modification.
Complete parts list and tech info for 811cc Stroker 101
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Stroker 101.
Stroker 741 with WL flywheels (750 cc).
To build a 45"/750cc 741/WL stroker, you will need the major parts below. Click here for a complete list of all parts needed.
1) Used WL flywheels. See notes on second-hand Harley parts below.
2) Used WL rods. See notes on second-hand Harley parts below.
3) New WL crankpin and big end assy. See note above.
4) IPE Stroker pinion shaft, P/N 39348WL.
5) IPE Stroker drive shaft, P/N 41044WL.
6) IPE thrust washer adapter, P/N TWAWL - you will need one of these. 
7) IPE Stroker Pistons, P/N 75494S. Note that these pistons have a 4 mm (approximately) "pop-up" like the factory Bonneville pistons, and need the cylinder heads to be cut out for this.
Complete parts list and tech info for 750cc Stroker 741WL
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Stroker 741. This engine has one of the prototype manifolds, seen on the 741 page, and big nipples to match.
Stroker 741 with XL flywheels (750 cc).
To build a 45"/750cc 741/XL stroker, you will need the major parts below. Click here for a complete list of all parts needed.
1) Used XL flywheels. See notes on second-hand Harley parts below.
2) New XL crankpin and big end assy (if you go with used rods).
3a) Used XL rods. See notes on second-hand Harley parts below. Alternative:
3b) New XL rod and big end assembly. Complete rod and big end assembly. The way to go for most stroker builders, as you probably can't rebuild a set of used rods for the same price unless you do all the work yourself.
4) IPE Stroker pinion shaft, P/N 39348XL.
5) IPE Stroker drive shaft, P/N 41044XL.
6) IPE Special pinion housing, longer and allowing for line honing of the main bearing housings (small lip around timing side crank case must be removed for this). We need to talk about the size of the bearing bore in your cam side crank case after it has been honed round. The OD of the pinion housings is finish ground to measure. P/N 20B101XL.
7) IPE Stroker Pistons, P/N 75494S. Note that these pistons have a 4 mm (approximately) "pop-up" like the factory Bonneville pistons, and need the cylinder heads to be cut out for this.
Complete parts list and tech info for 750cc Stroker 741XL
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Complete XL rod kit. New rods with honed races and pin bushings, crankpin, rollers, roller cages and nuts.
Notes on second-hand Harley parts. Updated with new info May 17, 2009
WL flywheels. Sorry, I can't help with these but, as 88,000+ sets were made, it should be possible to find one almost anywhere in the world. Make sure the tapers for the shafts are good.
XL flywheels. 900 or 1000cc "Ironhead" Sportster, 1957 to early 1981. Jeff Diamond of Victory Library (see link in right column) pointed out to me that the tapers for the shafts in Sportster flywheels changed in late 1981. So watch this point when hunting wheels. Sorry, I can't help with these either, but you should be able to find a set almost anywhere in the world. Make sure the tapers for the shafts are good. To convert for Scout use, you must lathe cut the stock thrust washer recesses on the outside flywheel faces to take Indian 27B174 thrust washers + you must use a slightly longer IPE pinion housing to make up for the narrower width of the XL flywheel assy. Housing bore is also bigger than stock to take the fatter pinion shaft.
WL rods. I can occasionally supply these, but you should be able to find a cheap set where you find the flywheels. Be aware that these rods invariably will need straightening before use (they are often both bent and twisted), as well as the usual honing back to round before new races are sized on the OD, pressed in to the correct depth and finish honed. New pin bushings must also usually be fitted and sized. 
XL rods. Same as above. A new XL rod kit from IPE is probably a better and cheaper alternative for most people. Jeff also pointed out that there are different lengths of Sportster rods, which allow more choices of compression distance, rod ratio, cylinder height and pop-up. There is a chart of Harley rod lenghts here.
Victory Library
There is a ton of good info here - including The Linkert Book. If you are interested in how your Linkert works in detail, in making it give its best, and maybe even in going beyond that, GET this book if you don't already have it. Lots of other interesting books on the Victory Library site. Jeff is one of my heroes for his commitment to getting to the the bottom of what makes our old junk tick, and for his willingness to share the results of his research.
 

Click to watch video
Here's a great video on YouTube of a Stroker Scout (not one of IPE's), to give you an idea of what to expect from a fully developed stroker engine. To get to this level of zip takes a lot of dedicated work, but a basic stroker kit is a good start.

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